VOL. 95, No. 2475

stein,' so far as we know no stereoisomer of the all-trans compounds has hitherto been prepared in thecase n > 3.In a related field, that of the natural polyenes, the

C40-carotenoids, methods have been used in some lab-oratories2 for the preparation of stereoisomers, viz.,reversible isomerization by refiuxing solutions, byiodine or HCl catalysis, and by melting crystals. Ir-radiation can also be effective. As the adsorptionaffinity of stereoisomers varies with the configuration,they can be separated by chromatographic analysis.We have now found that the methods mentioned

are applicable to the diphenylpolyenes, in particulardiphenyloctatetraene, and that the stereoisomers can

be separated by developing the chromatogram withbenzene-petroleum ether mixtures on calcium hy-droxide. The reversibility of the trans-cis shift be-comes manifest by spontaneous reisomerization, eachof the separated isomers yielding a mixture in whichthe all-trans compound prevails. So far two new

partially cis-isomers of diphenyloctatetraene have beenobserved below the zone of the starting material. Theyare followed by several minor zones which are underinvestigation. Since the adsorbates mentioned are

almost colorless, the developing of the chromatogramhas been followed by their fluorescence in ultravioletlight.We expect to study other synthetic polyenes by the

methods indicated.L. ZECHmEISTERA. L. IERosEN

GATES AND CRELLIN LABORATORIESOF CHEMISTRY,

CALIFORNIA INSTITUTE OF TECHNOLOGY

A SIMPLE MEANS OF RETAINING OILBETWEEN SLIDE AND

CONDENSER

THE condensers of most research microscopes are

optically designed for homogeneous immersion againstthe lower surface of the slide. If the air gap is leftopen, only a fraction of the numerical aperture ofthe immersion objective is utilized.

Unfortunately, many condensers are so constructedthat when a slide of the usual thickness is used, thegap between its lower surface and the top lens of thefocused condenser is about 1 mm. Cedar oil does notpossess sufficient surface tension to hold it in place

1 R. Kuhn and A. Winterstein, Helv. chim. Acta, 11: 87,116, 123, 144, 1928.

2 L. Zechmeister and P. Tuzson, Biochem. Jour., 32:1305, 1938, Ber., 72: 1340, 1939; A. L. LeRosen and L.Zechmeister, Jour. Am. Chem. Soc., 64, 1942, in press; F.W. Quackenbusch, H. Steenbock and W. H. Peterson,Jour. Am. Chem. Soc., 60: 2937, 1938; H. H. Strain,"Leaf Xanthophylls," Carnegie Institution of Washing-ton, No. 490, 1938; Jour. Am. Chem. Soc., 63: 3448,1941, etc.

in a gap this large. It soon runs to one side, and is,in general, so troublesome that most cytologists dowithout it except for particular critical figures.

This difficulty can be overcome by filling most ofthe gap with glass, leaving only thin spaces to befilled with oil. One obtains a piece of glass of theproper thickness (I used a thin slide), and cuts apiece which will a little more than cover the top lensof the condenser. One puts a drop of oil on this glassinsert and lowers it onto the condenser. One lowersthe condenser slightly, then puts a drop of oil onthe under surface of the slide and places the slide onthe stage. One raises the condenser back into focus,and optical contact is thereby established. Since theglass is of the same refractive index as the oil, it isas if the gap were filled entirely with oil. If theglass insert is not too thick, there will be no difficultyin focusing. If it is not too thin, there will be notendency for the oil to run out. Several differentinserts may be needed, for use with slides of variousthickness. One can conveniently keep the condenserimmersed during an entire working day. Dependingon the size of the hole in the stage, a greater or lesserarea of the slide can be searched without smearing.Then one must pause, wipe the oil off the undersurface of the slide, put on a fresh drop in theproper place, and start again.

This method is so simple that it has probably beenused before. However, it newly occurred to theauthor, and was new to several cytologists to whom itwas mentioned.

R. H. MAcKNIGHTWILLIAM G. KERCKHOFF LABORATORIES

OF THE BIOLOGICAL SCIENCES,CALIFORNIA INSTITUTE OF TECHNOLOGY

NEW BOOKSARNOT, F. L. Time and the Universe. Pp. 76. Aus-

tralasian Medical Publishing Company, Limited.Collected Reprints, 1941. Illustrated. Woods Hole

Oceanographic Institution.COTTON, C. A. Landscape. Pp. 301. Illustrated. Cam-

bridge University Press. $4.75.CURTMAN, LOUIS J. Introduction to Semimicro Quali-

tative Chemical Analysis. Pp. 377. The MacmillanCompany. $2.75.

DUNCAN, JOHN CHARLES. Essentials of Astronomy. Pp.181. Illustrated. Harper and Brothers. $1.85.

FLOHERTY, JOHN J. Sentries of the Sea. Pp. 220. Il-lustrated. J. B. Lippincott Company. $2.00.

HOWE, HARLEY. Introduction to Physics. Pp. 559.The MeGraw-Hill Book Company. $3.75.

MONTAGU, ASHLEY. How to Find Happiness and KeepIt. Pp. 298. Doubleday, Doran and Company. $2.95.

NYSWANDER, DOROTHY B. Solving School Health Prob-lems. Pp. 377. The Commonwealth Fund. $2.00.

REICHENBACH, HANS. From Copernicus to Einstein.Pp. 123. Philosophical Library, Inc. $2.00.

WILLIS, L. G. Bibliography of References to the Litera-ture on The Minor Elements and Their Relation toPlant and Animal Nutrition. Third supplement tothird edition. Pp. 78. Chilean Nitrate EducationalBureau, Inc.

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JUNE 5, 1942 SCIENCE-ADVERTISEMENTS 9

SCIENCE-SUPPLEMENT VOL. 95, No. 2475

SCIENCE NEWSScience Service, Washington, D. C.

THE X-RAY MICROSCOPEAN "X-ray microscope" invented by Professor W. L.

Bragg, of the Cavendish Laboratory of the University ofCambridge, is the newest instrument for peering into theinnermost structure of matter. By its means can be seen

the actual arrangement of the atoms in one layer of thecrystal.The instrument is not yet fully perfected and at present

applies to only one special case. But Professor Bragghopes to extend its applications and believes that it willthen be a useful aid in crystal analysis.

The X-ray analysis of crystal structure, which won theNobel prize for Professor Bragg and his father, the lateSir William Bragg, is of immense importance in allbranches of both war-time and peace-time industrial re-

search. On the crystalline structure depends the strengthof steel girders, the toughness of armor plate, the hard-ness of tool steel, the properties of aluminum alloys, thelubricating qualities of paraffins and of graphite, thestretching of rubber, the covering power of pigments; infact, nearly every aspect of the behavior of a solidsubstance.But X-rays passing through a crystal do not directly

reveal its structure. They produce a "diffraction pat-tern " of complicated design from which the positionsand spacings of the atoms must be calculated. This givesthe arrangement in a particular plane. To get the truearrangement in space, several such patterns must bephotographed by passing the rays through the crystal indifferent directions. A three-dimensional model can thenbe made. This is a long and laborious process.

Instead of making a drawing showing the arrangementin a particular plane, Professor Bragg 's apparatus formsan optical image of it which can be viewed through an

ordinary optical microscope. (The name "X-ray micro-scope" applies to the whole apparatus.)He drills a number of small holes through a brass plate.

The sizes and arrangement of these holes are determinedby the diffraction pattern. The plate is placed in thepath of a beam of ordinary parallel monochromatic light.This light in passing through the small holes produces a

diffraction pattern of its own which, however, on accountof the carefully calculated sizes and spacings, is a replicaof the arrangement of the atoms in the crystal, each spotrepresenting an atom. The image is focused and viewedthrough the microscope.

Thus, X-rays passing through a crystal are diffractedby the structures they encounter, but produce a patternbearing no resemblance to this structure. By rediffract-ing this pattern backwards, so to speak, with ordinarylight, Professor Bragg obtains a visible image of theatomic arrangement that produced it.To get a good image, the holes in the plate must be

accurately dimensioned and spaced to better than half a

wave-length of the light used. On account of this diffi-culty, Professor Bragg has lately devised an improvedmethod. An enlarged drawing is made in which the holesare represented by solid black circles. This is then photo-

graphed and reduced to the proper size, the black circlesbeing in effect converted to transparent holes. The use

of this in place of the brass plate gave much better defi-nition.The new method was reported to Nature, with photo-

graphs made with the "X-ray microscope," and draw-ings of the same crystal structure calculated from X-ray

diffraction patterns, showing close correspondence betweenthe two.

POSSIBLE AERONAUTICALDEVELOPMENTS

THREE aeronautical developments would upset the pres-

ent more or less new military aviation race throughoutthe world-a successful gas turbine engine for airplanes,a practical rocket plane and the realization of an airplanewing structure that would prevent the air becoming tur-bulent as it flows over it.

Dr. Jerome C. Hunsaker, of the Massachusetts Insti-tute of Technology, aeronautical engineer and chairmanof the government National Advisory Committee forAeronautics, in speaking before the Harvard War Insti-tute listed these as the three possible developments thatmight with some rapidity spring a surprise. It is knownthat engineers throughout the world have been working,attempting to achieve these objectives.A gas turbine would be an escape from the very real

task of lubricating ordinary internal combustion enginesat very high temperatures, now a limit to efficient opera-

tion. Present engines waste a third of the gasoline 'spower in heat. Successful gas turbines operating on

waste gases from diesel engines and the oil refining proc-

ess have been perfected and are in use in Switzerland andin this country. The gas turbine in the airplane wouldeliminate the cooling system and also allow operation at10,000 to 12,000 revolutions per minute instead of the3,000 of the present engines.

Rocket planes avoid all engines and propellers, the pro-

pulsion being given by the kick of the rush of the gases

out of an orifice at the rear of the plane. The Italianshave already flown a small rocket plane from Milan toRome. Rocket propulsion would be particularly effectivein the high altitudes where the air is rare because therocket kick doesn't need air to operate.Making air flow smoothly over an airplane wing so as

to maintain its untroubled characteristics might reducethe resistance or drag offered by the airplane by half.This is a major problem that might make a big differencein the performance of airplanes in the future if it couldbe solved.-WATsoN DAVIS.

THE NATIONAL ROSTER OF SCIENTIFICAND SPECIALIZED PERSONNEL

BY January, 1943, a new force of 172,000 young men

and women will be ready to tackle the technical problemsof war for Government and war industries. Already theyare streaming from colleges, universities and technicalschools as a result of speed-ups in educational programs.

10

SCIENCE-SUPPLEMENT

This is shown in a count just completed of collegestudents being trained for 103 war-vital occupations as

picked by the National Roster of Scientific and Special-ized Personnel. The survey was conducted by the Ameri-can Council of Education at the special request of theNational Resources Planning Board.A majority of the 812 institutions surveyed are already

teaching a capacity load of students in the fields wheremanpower shortages are developing, was indicated by Dr.C. S. Marsh, vice-president, in his report of the survey.

Courses are being compacted, vacations shortened and thethree-term college year is being substituted for the time-honored semester system.

Graduation comes at least a month earlier than it usedto in the majority of the institutions studied. One tech-nological school is delivering to industry twice its usualnumber of trained youth, and is doing it in sixteen monthsless time.

Seasonal peaks are also being ironed out of the college-trained manpower supply by changes in teaching policyand speed-ups of courses. Although June is still thefavorite month for cap-and-gown processions and theawarding of degrees, there is now a steadier flow through-out the whole year. This is the tempo at which 1942'sgraduates will become available for war employment:

Already graduated in February or March, 12,000; inApril or May, 43,000; June or July, 74,000; August or

September, 13,000; December or January, 1943, 29,000.Special courses have been organized by colleges to aid

in the war program. Many have night classes in theESMDT (engineering, science, and management defensetraining) courses administered by the U. S. Office ofEducation. Others have turned over dormitories andclassrooms for use of Army and Navy fliers. Laboratorieshave been turned over to the Government for militaryresearch and faculty members have been loaned.

Special courses bearing on war problems, such as

camouflage, explosives, tactics, map-making, radio com-

munication, cryptography and military law have beenorganized.The colleges and universities are facing a manpower

problem of their own, meantime. Skilled scientists are

being taken from teaching jobs to carry on military re-

search. Enrollments of students are dropping off, too,but this does not balance the loss of faculty members.The professors most needed in war research are thoseteaching in the physical sciences. Their loss is not bal-anced by the drop in numbers of music students. Studentenrollments have decreased most sharply in the liberalarts courses, teacher training and law schools.-MARJORIEVAN DE WATER.

ITEMSMEDICAL students who have completed advanced Re-

serve Officers' Training Corps courses will have a chanceto complete their medical course before being called toactive duty, according to the War Department. If theyhave been accepted as matriculants in an approved medi-cal school, they will be commissioned second lieutenantsin the U. S. Army and placed on deferred duty status.They will be commissioned in the arm or service in whichthe training was received rather than in the Medical

Administrative Corps. Those who have completed allrequirements for the commission before entering medicalschool except the practical training at the appropriateservice school will be required to attend the service schoolif the date of their entrance into medical school permits.If it does not, they will be permitted to withdraw fromtheir R.O.T.C. course contracts, will be commissioned as

second lieutenants in the Medical Administrative Corpsand will be placed on deferred duty status until theirmedical training has been completed or discontinued.

PINE, spruce and other conifer seedlings frequently failto grow when transplanted into prairie soil. Cause forthese losses has been traced to lack of a certain type offungous growth on their roots, by A. L. McComb and J.E. Sass, of the Iowa State College. Seedling loss was

particularly troublesome on new nursery sites, where seed-lings of jack pine, Norway spruce and other coniferspecies produced weak, straggly growth, or died whenonly a few inches high. Roots of these seedlings were

found to be uninfected with the fungal threads knownas mycorrhiza, which are found in the root tissues ofhealthy trees. Botanists believe that these fungi aid thetrees in absorbing food materials from the soil. Thesituation was remedied by inoculating the soil with sur-

face litter from an older coniferous plantation, which con-

tained the necessary fungi. Phosphorus seems to be thechief plant food material which the fungi enable thetrees to absorb. Application of phosphate fertilizerwithout soil inoculation resulted in satisfactory growth,and the fungi appeared on fertilized seedlings.

PERISHABLE foods are now being made to refrigeratethemselves on American cargo ships, using an ingeniousplan made public by the United States Department ofAgriculture. Lard, chilled to a zero temperature or lower,is the refrigerating agent. By lining the holds of ocean-

going ships with insulating material, packing large con-

tainers of the refrigerated lard to form a floor and wallsaround perishable foodstuffs, placing more lard over thetop, and adding a final cover of insulation, the shipmentis kept safely cold until it reaches its destination inEngland or Russia. The system has been adopted to keepAxis submarines from stopping shipment of perishablesto United Nations ports by systematically sinking refrig-erator ships. It has the added advantage of saving spacewhich refrigerating machinery would occupy.

USE of sound waves to improve sulfa drug treatmentof wounds, infections and burns is announced by Dr.Leslie A. Chambers, Dr. T. N. Harris, Dr. Francis Schu-mann and Dr. L. Kraeer Ferguson, of Philadelphia, inthe Journal of the American Medical Association. Thesonic vibration is used to break up sulfathiazole crystalsinto microscopic bits which when suspended in water or

salt solution gives a preparation with the consistency ofthick cream. This preparation can be injected throughfine gauge hypodermic needles, which is usually not pos-

sible with neutral suspensions of ordinary sulfa drugcrystals because of their larger size and irregular shape.The microanalysis of sulfathiazole can get to work fasterat their job of stopping germ invasion because they dis-solve more rapidly nd do not clump or cake.

JUNE 5, 1942 11

12 SCIENCE-ADVERTISEMENTS VOL.

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SCIENCE-ADVERTISEMENTS VOL. 95, NO. 247512

JUNE 5, 1942 SCIENCE-ADVERTISEMENTS 13

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JUNE 5, 1942 SCIENCE-ADVERTISEMENTS 13

14SINEAVRISMNSVL 5 N.27

Spepo Miroscopes in use in an Army Laboratory. Official Photo-Lown Field*

The Greatest Health Crusade in HistoryHealth is"-the first prerequisite of a

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*This, of course, does not constitute an indorsement by the War Department or by any other Government Agency.

14 SCIENCE-ADVERTISEMENTS VOL. 95, NO. 2475